What if advanced alien invaders wanted to get rid of humans?

One way is described in the SF novel "Footfall".

Aliens come to our Solar System in a huge spaceship propelled by a Bussard ramjet. They use meteoroids and asteroids as weapons. This included a large asteroid dropped into the Indian Ocean, causing a tidal wave which wiped out all the coastal lands around that ocean.

In the novel they didn't wipe out all the humans, but they had the power to do so. And these aliens weren't really that much more advanced than we are.

They'd leave us alone and let us keep on doing it ourselves. Maybe to speed up the timeline, they'd engineer a few conservative governments. They love to kill as much as possible. 

I think it would partly depend on the aliens' culture.  For example, two people might have squirrels that they want to keep away from their garden.  One person has no qualms about using killer traps and poison, while the other will put up netting and non-lethal devices to scare them away.

The laziest way to wipe us out might be a plague engineered to defeat human-based immunities.  Or perhaps locate each individual person, and zap them into their component elements.  A more compassionate culture might give us something that is more pleasurable and satisfying than sex, plus technology to take care of the basic needs of living, then just wait for our population to zero out over a thousand years.  Or, analogous to the gardener who has live catch traps, the aliens might relocate all humans to another world suitable for their life.

You are assuming that (if) aliens exist then they would want to remove us for some nefarious reason, why?

well would solve one major problem .. its true alians do like KFC ..

aliens w tech a thousand years more advanced can do what they want

The aliens would make a virus that is transmitted easily from person to person. It would quickly spread all around the world and become an epidemic. 

They have already done this. 

It went quite well with covid and the media at a test run.

I would fight them off with Two Bananas, A Bar of Soap and my Faithful Dog Fido

they would be over 100000 years old when they got here and that would be from the nearest galaxy

many many ways. Easiest is to take a medium sized rock, accelerate it to near light speed and aim it to hit earth.